Breakfast at Murphy's (or why the toast lands butter-side down)

By Robert Matthews, Science Correspondent

12:00AM BST 27 May 2001

NO longer ridiculed as a myth, scientists have proved that Murphy's Law is true: if toast can land butter-side down, it will do.

Today, The Telegraph exclusively reveals the outcome of the world's biggest-ever investigation into Murphy's Law, which states that, if things can go wrong, they will go wrong. In a mass experiment carried out in schools across the country, schoolchildren put toast on to plates, and watched what happened when the slices slid off. And they proved beyond reasonable doubt that Murphy's Law is at work at the breakfast table.

Of almost 10,000 trials, toast landed butter-side down 62 per cent of the time - far more often than the 50 per cent predicted by sceptical scientists. Based on so broad a study, the probability of achieving so big a difference by chance alone is vanishingly small. So, for optimists everywhere, there is no escaping the bleak reality of Murphy's Law.

For me, as a confirmed pessimist and scientific consultant to the project, the outcome of the mass experiment marks the end of a seven-year quest to confirm my darkest suspicions: that things go wrong because the universe is made that way.

My quest began in June 1994, after I read a letter in New Scientist magazine. Colin Morgan, from Warrington, claimed to have found the reason why toast so often lands butter-side down: as it falls off a plate, it doesn't have time to complete a full spin, bringing the buttered side back up again before hitting the floor. Anyone doubting his explanation should perform an experiment, said Mr Morgan: "Push a piece of bread slowly over the edge of a table. See?"

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Along with, I suspect, many other people, I initially thought that Mr Morgan had simply not performed his experiment often enough. Had he done so, he would surely have confirmed what every scientist knew: that toast is just as likely to land butter-side up as down.

Indeed, a team of scientists had proved precisely this in an experiment carried out in 1991. After getting people to toss buttered bread in the air 300 times, the results were statistically indistinguishable from the 50:50 split of a coin-toss. It seemed obvious that Murphy's Law of toast was really nothing more than selective memory, with people remembering only the 50 per cent of times when the toast lands butter-down.

After repeating Mr Morgan's experiment with a paperback book, however, I realised that he was on to something. The book unquestionably had a tendency to land face-down, slowly spinning as it fell to land. This clearly had implications for toast, which usually ends up on the floor after sliding off plates - not after being tossed into the air. It dawned on me that the "scientific" experiments had not disproved Murphy's Law at all: the scientists had simply performed the wrong experiment.

Detailed calculations of the dynamics of tumbling toast confirmed my suspicions, and revealed something else: that the presence of butter was more or less irrelevant. Neither its weight nor aerodynamic properties had much effect on how toast landed. The crucial factor is purely height - and toast sliding off a plate spins so slowly that only if it falls from heights above 8ft does it have much hope of regularly landing butter-up.

Publication of my calculations in the European Journal of Physics in 1995 sparked an enormous response: television crews from countries from Australia to Brazil turned up, demanding to see toast fall butter-down on my kitchen floor. Yet, all the while, I was nagged by the fact that my work was, in the end, "theoretical". I still wasn't sure whether real toast obeyed my back-of-the-envelope estimates.

After that, and putting my doubts about toast to one side, I moved on to investigate other notorious manifestations of Murphy's Law, such as why the queue you're in is so often beaten by the one next to you, and if the place you're looking for in the road atlas can lie on an awkward part of the map, it will. Time and again, these myths turned out to have a solid basis in fact. My research won awards, and I was invited to give a discourse on my findings to the Royal Institution. Yet still my worries over tumbling toast remained.

The chance to resolve them finally came a year ago. Lurpak, the butter manufacturer, was setting up an educational project for schools, and wondered if I could devise an experiment based around Murphy's Law of toast. Together with staff from the Maths Year 2000 programme of the Department for Education, we drew up plans for the biggest-ever investigation of Murphy's Law, involving schoolchildren from across Britain.

Here was a golden opportunity to put my calculations to the ultimate test: a nationwide study that would produce thousands of data-points. The experiment consisted of three tests. The first was aimed simply at finding out whether toast really did land butter-side down more often than not. To perform the experiment, each pupil was asked to put a piece of toast on a plate, let it slide off 20 times and note which way up it landed.

The second experiment probed Murphy's Law of Toast a little deeper. This time, the toast had nothing on it apart from a letter "B" written on one side in marker pen. My calculations suggested that butter played little role in deciding the fate of toast. If they were right, then even toast marked only with a "B" should still land more often "B"-side down.

The third experiment studied the effect of height on tumbling toast. Secondary school students were asked to let toast tumble from heights above 8ft. If the theory was correct, this would lead to toast landing butter-side up significantly more often than down.

The Lurpak Tumbling Toast Test began in March and ended earlier this month; more than 1,000 children took part, with toast tumbling off plates more than 21,000 times - making it by far and away the biggest-ever study of Murphy's Law.

The results, I'm relieved to say, were in complete agreement with the theory. The first experiment, with its 62 per cent face-down rate, clearly confirmed Murphy's Law. In the second test, designed to probe the effect of butter, the toast still landed 58 per cent of the time on the side marked "B" - a rate just four per cent lower than that with butter. This confirmed that, despite what many believe, butter is not the prime cause of the trouble.

The real culprit was revealed by the outcome of the final experiment. Of more than 2,000 tumbles from heights above 8ft, the toast landed face-down only 47 per cent of the time - confirming that it is only from such a great height that toast has much chance of landing butter-side up.

The children reported their results via the Maths Year 2000 website and it was clear that they relished the chance to use science to test their own theories about what was happening. Many came up with suggestions for beating Murphy's Law - along with evidence to back their claims. My favourite was from Hannah, seven, at the Good Shepherd Primary School in west London: "Butter the other side."

Thanks to their efforts, the cause of a familiar source of frustration has finally been identified. Toast lands butter-side down because we humans aren't tall enough to let it land any other way. I am left with only one small worry. If Murphy's Law really is true, how come all the experiments went so well?